The note names are written on the keys. Notes written in the two most common clefs (Treble clef and Bass clef) are connected to the piano. All notes can be written in an infinite number of ways. The most common enharmonic notes are included. A line going from a long red box means the notes go to the same key on the piano. Even though the drop-down keyboard shows only two octaves of notes (48 to 72), a number can be put in manually to get any note. To change octaves, simply add or subtract 12.

There are 128 notes on the MIDI keyboard, numbered from 0 (C-1, about 8.18 Hz) to 127 (G9, 12500 Hz). Each note is 1 higher than the previous, and the ratio of frequency is always 122 (approximately 1.06), with A4 being 440 Hz.

Clef Note MIDI number Frequency
Bass C3 48 131 Hz
C♯3/D♭3 49 139 Hz
D3 50 147 Hz
D♯3/E♭3 51 156 Hz
E3 52 165 Hz
F3 53 175 Hz
F♯3/G♭3 54 185 Hz
G3 55 196 Hz
G♯3/A♭3 56 208 Hz
A3 57 220 Hz
A♯3/B♭3 58 233 Hz
B3 59 247 Hz
Bass and Treble C4 (middle C) 60 262 Hz
Treble C♯4/D♭4 61 277 Hz
D4 62 294 Hz
D♯4/E♭4 63 311 Hz
E4 64 330 Hz
F4 65 349 Hz
F♯4/G♭4 66 370 Hz
G4 67 392 Hz
G♯4/A♭4 68 415 Hz
A4 69 440 Hz
A♯4/B♭4 70 466 Hz
B4 71 494 Hz
C5 72 523 Hz